Great first holster! I would only suggest you pull those stitch lines in a bit. The revolvers, being less square, are much more difficult to estimate the location of the stitch lines than the automatics. You probably have an idea of where you can move them, now that you've made the first one. In the future, with a new model, or with this one, you can use a strip of leather equivalent to the weight you intend to use for the holster to wrap around the gun and get a total circumference. If you are going to wet form, you can case the leather strip prior to measuring. I look forward to seeing your next one.

I have not done this with a flat back holster. I guess that my point was, with a vacuum press, you can get even pressure over the tooling area and therefore some molding without destroying the tooling, provided that the tooling is deep enough. Thanks for your praise. It means a lot coming from such a skilled craftsman and artist such as yourself. I, however, was less than pleased and fairly critical of that holster. Let's just say that I learned...and relearned, some lessons with that one. I did feel that the tooling withstood the vacuum press fairly well, though.

I tend to err on the side of a bit tight. Leather will stretch, but it will not, generally speaking, shrink. Also. There can be variance even within a particular model. I made a holster for my dad's Springfield Loaded 1911 using my own Springfield Loaded. Mine was parkerized and his was stainless. It fit my gun like a glove, but was tight on his. After a day or two in the holster with a freezer bag around it, his gun fit great. In short, I would make them a bit snug and inform the customer on ways to stretch, if required. Plasic bag, business card, etc. There are many ways to accomplish this.
Also, you have come to the right place. The folks on thus forum are a wealth of knowledge, and very generous with it. Good luck, and please post some pics in this section as well.

I have one, use it on double layer 6/7 oz lined with 4/5 oz holsters, among other projects, and like it very much. I do try to protect it from sharp edges. If you look in the picture you will note that there is a rag around the grip of the 45.

I have tried this with a 50/50 holster. Little to no boning. Very tight stitch lines. Cheap vacuum press, but works very well. I recommend deep tooling. Check out this guy.
http://www.roarockit.com/skateboard-building/thin-air-press/tap-kits/thin-air-press-kit-26x28/#.WMXL0ctlDqA